A formic acid does not generate CO at a low reaction temperature (20 to 100° C.) under specific reaction conditions, easily discharges gas products (hydrogen and carbon dioxide) out of the system, has a relatively low hydrogen production cost (about 700 won/1 g H2), and is produced by means of regeneration of products (circulation of CO2). Due to such advantages, in these days, the formic acid attracts great interests as a hydrogen source of a polymer electrolyte membrane fuel cell (PEMFC).
For the decomposition reaction of a formic acid, there are two paths as follows. Carbon monoxide produced by a dehydration reaction poisons a platinum catalyst of the PEMFC which is a mobile fuel cell. Thus, a study for developing a catalyst capable of suppressing the dehydration reaction and having great activity to a dehydrogenation reaction is being actively performed.HCOOH→H2+CO2 (dehydrogenation reaction)  (1)HCOOH→H2O+CO (dehydration reaction)  (2)
However, the formic acid decomposition reaction is known as decreasing its activity as the concentration of the formic acid increases. This is because CO is accumulated at the catalyst when a high-concentration formic acid is used. If a formic acid of about 9.9 M (45 wt %) is used, the activity is rapidly lowered to reduce the gas generation rate, and it is known that only 19% of the formic acid is decomposed for about 2 hours 30 minutes.
Table 1 below comparatively shows a weight of fuel to have energy of 1000 Wh. In order to compare weights of fuels, the performance of a commercial fuel cell system, manufactured by Horizon Fuel Cell Technologies, using 25 wt % of NaBH4 as a solution was referred to. If 12 wt % of formic acid is used, 13.19 kg of fuel is required to have energy of 1000 Wh. This is about 10 times of the weight of 25 wt % of NaBH4 solution. In a mobile fuel cell system, an energy density is most important. This is because a fuel cell system of the same weight can be used for a longer time without recharging as the energy density is greater.
TABLE 1FuelWeight (kg)25 wt % NaBH4 solution1.3012 wt % formic acid solution13.19
In the existing technique, a liquid homogeneous catalyst and amine serving as a reaction accelerator are used to attempt a hydrogen generation system, but the hydrogen generation rate becomes unstable as the operations repeat, due to evaporation of amine and the deteriorated activity of catalyst.